For a Boolean object named Mixer, which user extended attribute will historize the message pair for the attribute?

The correct choice for historizing the message pair for the Boolean object named Mixer is Mixer.MSG. This attribute is specifically designed to store message data associated with the Boolean states of the Mixer object, allowing for tracking changes in state as well as the messages that may correspond to these changes.

Historizing the message pair is crucial because it captures both the value change of the Boolean attribute itself (whether it is true or false) and potentially includes contextual information, such as why that change occurred, enhancing the understanding of system behavior and decisions made during operational states.

An alternative attribute, such as Mixer.History, might imply general historical data logging but does not specifically indicate the storage of message pairs. Similarly, while Mixer.State or Mixer.Value could relate to the actual state of the Mixer object, they do not directly encompass the notion of message historization, making them less suitable for the desired function. Thus, Mixer.MSG is the most appropriate for the requirement of historizing the message pair.